kellogg



(No Model.)

M. G. KBLLOGG. MULTIPLE SWITCHBOARD.

Patented Oct. 26,1897.

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@Zag/dw?? NTTED STATES PATENT Price.

MILO G. KELLOGG,'OF CHICAGO, ILLINOIS, ASSIGNOR TO THE K ELLOGG SVITCIIBOARD AND SUPPLY COMPANY, OF SAME PLACE.

MULTIPLE SWITCHBOARD.

SPECIFICATION forming part of Letters Patent No. 592,341, dated October 26, 1897.

Application filed December Z1, 1889. Serial No. 334,518. (No model.)

To all whom it may concern,.-

Be it known that I, MILO G. KELLOGG, of Chicago, in the county of Cook and State of Illinois, temporarily residing at Stuttgart, in the Empire of Germany, have invented certain new and useful Improvements in Multiple Switchboards for Telephone-Exchanges, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to a telephone exchange system in which parts of the lines are metallic-circuit lines and part of them are singie-circuit lines; and it consists of apparatus for and a system of switching such lines of the exchange in the operation of the exchange system and a system of testing the lines to determine whether they are in use.

In the drawings illustratingr myinvention, Figures la and lb represent sections of two multiple switchboards of the exchange to which the same lines are connected. Fig. 2 shows adiagram of the boards,with the mainline apparatus and connections necessary to illustrate my invention. Fig. 3 shows a dia gram of an operators cord system to be used in connection with the boards. Fig. 4 shows a subscribe1"sstation apparatus to be used on the metallic-circuit lines. Fig. 5 shows an operators test system.

In Fig. 2, A is a sectional view of the switchboard shown in Fig. l, and A is a sectional view of the switchboard shown in Fig. l, each as indicated by the line CZ e.

I place as many boards in the central otlice as are found necessary or desirable in order to properly operate the exchange. On each board is a spring-j ack or other suitable switch for each line. Each switch has a contact spring which normally bears on an insulated contact-point and has a contact-piece insulated from the rest (except by the circuit connections) and is adapted to receive a loopwhich the springs normally bear, and jj thc insulated contact-pieces of the switches. Z Z are the switch-holes. o b are the rubber strips, on which the metal parts of the switches are mounted, as shown, and through the fronts of which are the switch-holes Z Z. The contact-piecesjj are so placed that a test-plug or similar device may readily be applied to them. The holes Z Z are adapted to receive the switchplugs, (shown in Fig. 3 and marked D 1),) and when a plug is inserted into a switch it raises the spring g from the contactpoint h, and the spring g and contact-piecej are in contact with the two contact-pieces, respectively, of the plug.

w and a are the line-annunciators for the two lines shown.

R is a rheotolne or mechanical circuitbreaker containing a clockwork-movement actuated by a spring. It contains an oscillating bar iixed to the verge-shaft and standing at right angles to it. points is connected with the bar or with the shaft in such a way that their contact is alternately made and broken with the oscil` lations. The pair of contact-points are properly insulated and are connected into the circuit, as indicated, for the rheotome. Instead of the rheotome shown any form of mechanical or electrical rheotome or any apparatus which changes the electrical condition of the line so that the change will be indicated on the test receiving instruments may be connected into the circuit, as indicated, for the rheotome.

Two lines are shown in Fig. 2, one of them a metallic circuit line, the two sides or branches of which are marked line No. ln and line No. lb, respectively, and the other a single-circuit line marked line No. 2.

The circuit of the sin gle-circuit line is as follows: from the subscribers ground, through his station apparatus, (which may be of the usual form of apparatus,) thence through the line and the pairs of switch contact-points g h ofthe switches, successively, of its switches on the several boards, going in each case to the point h first, and thence through the lineannunciator to the common wire of the lines in which is the rheotome. This common wire is grounded, with the rheotome between the A pair of contact# IOO follows: OneA side or branch of the line ground and the connections of the lines with it. All the contact-pieces jj of the switches ofthe line are connected together and to the line, the connection being between the switch contact-points and the subscribers station.

The circuit of a metallic-circuit line is as say line No. la, as shown-is connected with all l:he contact-pieces j j of its switches on the boards. The other branch ofthe line-say line No. lb-passes successively through the pairs of contact-points g h of its switches on the several boards, passing in each case to the-spring first. It then passes through its annunciator to the common wire, in which is the rheotome.

In the subscribers-station apparatus for metallic-circuit lines (shown in Fig. at) l is the telephone-switch. 2 is the calling-generator. 3 is the signal-receiving bell, and 4. `is the subscribers telephone. These parts may be the usual forms of apparatus, and may be connected as shown or in other ways, so as to produce the required results. The generator, however, is modied and is as shown. When it is notin operation, the subscribers line is open to the ground at his station. While it is being operated the line is aut-omatically grounded, with the armature-coil between said ground connection and the normal ground connection of the line at the central ofice.

The modification consists,essentially, in the number and arrangement of the contactpoints of the automatic device. The automatic device shown is a modification of a form very generally used. It consistsin a V-shaped attachment to the hub of the driving-wheel, a pin in the shaft, which engages in this V- shaped arrangement, and a spring which presses against the wheel and brings the pin normally in the center of the V-shaped arrangement. The contact-points and circuits are substantially as shown. One side or branch of the line connects with the frame of the generator, as does also one end of the armature-coil and the spring o of the automatic device. The other side or branch of the line connects to the insulated -spring o', which bears on an insulated piece on the armaturel shaft, to which the other end of the armaturecoil is connected. The contact-point with which the spring of the automatic device is pressed into contact when the generator is operated is connected to the ground. The side or branch of the line which is grounded at the central office is 'the one connected to said insulated spring o of the generator.

In the operators cord system shown in Fig. 3, D D are two loop-plugs. Y isa looping-in switch for the plugs, and o a'clearing-out annunciator. 1f is the operators telephone, and B is her calling-generator. m fm. are the two contact-pieces of the plug. They extend to the bottom of the plug,as shown,and normally rest on the metal piece o, which thereby then bringsv them into electrical connection. The

contact-pieces m m of the two plugs are connected to the two levers of the switch Y by flexible conductors, as shown. LThe other contact-pieces of the plugs 'm m are connected to the ground through flexible conductors, as shown. Only one pair of plugs, with their cords, switch, and clearing-out annunciator, is shown. Other pairs may be added to the system in a manner which will be apparent to those skilled in the art.

In the operators test system shown in Fig. 5, T is the test-plug, connected by a flexible conductor to the test receiving instrument S, and thence through the test-battery B to the ground.

The test receiving instrument Iis of such a character that it will respond to variations in the strength of the test-current. In the drawings a testing-bell is shown with its armature supported in air by a spring only, so that as the-current grows stronger or weaker the armature will vibrate. The test receiving instrument universally used in telephone-exchanges is the operators head telephone, and such a device may be used with this exchange.

Each operator has a test system and a cord system, and they are conveniently mounted and arranged for her work.

The switching between the various lines of the exchange is as follows: Vhen an operator receives a call on a single-circuit line assigned to her board, she places one of the plugs of her system into the switch of the line, so that the piece 'm' is in contact with the switchpiece j, and placing the levers of the switch Y so that her telephone is in circuit iinds out, by conversation, what line is wanted. The circuit of the line is complete to the ground through the connect-ion between the contact# pieces of the other plug by means ot' the piece o, on which they normally rest. When she finds out what line is wanted, she tests it, as

will hereinafter be described, and if she finds it to test free she places the other plug of the pair into its switch, so that the contactpiece m' of the plug is in connection with the contact-piece j of the switch. If the second line is also a single-circuit line, the circuit is complete between the two lines from the subscribers ground of one line through the switch-cords connected to the plug-contacts m m to Vsubscribers ground of the other line. If the secondline is a metallic-circuit line, there is a complete circuit as follows: from the ground of the single-circuit line through the circuit of the line, the contact-pieces m' m of the plugs used, and the cords connecting them together, through the circuit of the metallic-circuit line to the contact-piece 'm of the plug which is in its switch, and thence to the ground through Ithe cord conductor which is connected with the piece. When an operator receives a call on a metallic-circuit line assigned to her board, she places one of the plugs of her system into the switch of the line, and placing the levers of the switch Y so that her telephone is in the circuit finds IOO IIO

out, by conversation, what line is wanted. The circuit of the line is complete when the plug is in the switch, because the two contact-pieces of the other plug of the pair are connected or bridged by means of the metal piece o, on which they rest. When she finds out what line is wanted, she tests it to see whether it is busy or not, and if it is not busy she places the other plug of the pair into its switch at her board. If the line which she connects to is a single-circuit line, she places the plug in its switch so that the contact-piece m is in connection with the piece j of the switch. There is a complete circuit of the two lines from the subscribers ground, the contact-pieces m m of the two plugs, and the cord connecting them together, thence through ,the circuit of the metallic-circuit line to the contact-piece m of the plug which is inserted into its switch, and thence to the ground through the cord which is connected with the piece. If the line which she connects to is also a metallic-circuit line, the lines are connected into a complete circuit as follows: from the ground through one contact-piece m to one line, thence through the circuit of the line, the contact-pieces m m, and the cords which connect them to the other line, thence through the circuit of the other line and the contact-piece m of the plug connected with it back to the ground.

In each case where a plug is inserted into the switch of a single-circuit line it is so inserted that the contact-piece m is in connection with the contact-piece j of the switch. The other contact-piece of the plug is then connected with the ground, but it does not affect the operation of the system.

lVhen any line in the system, whether single or metallic circuit, is not switched for use, there is a complete circuit from its contactpieces j j and the switch contact-points g 7L of the line to the rheotome and thence to the ground; but when the line is switched at any board the circuit to the rheotome and ground is interrupted at the pair of contact-points g 7L used. It follows that when the operator applies her test-plug (grounded through her test receiving instrument and battery, and the instrument and battery constructed so that the instrument will sound or respond when they are on closed circuit with the rheotome toits vibrations) and the instrument responds that the line is not switched at any board, and when it does not respond that the line is switched at some board. The operator can therefore determine, on testing, whether or not a line is switched.4

The test-circuit of a single-circuit line may be traced from the grounded operators test outiit through the two branches of the line, one branch including the line conductor and the ground at the subscribers station and the other branch including the switch-contacts and the office ground through the rheotome. Thepresence of the rheotome in one of these branch circuits causes a variation in the strength of the test-current passing through the test receiving instrument.

The test-contacts are connected tothe line conductors permanently or under all conditions, whether the line is or is not switched for use.

It will be seen from the description of the system of switching and testing, as above described, that the operators can make all the necessary connections and testing for a telephone system with combined single and metallic circuit lines, that the operations they go through with for each connection are the same whether the lines switched be singlecircuit or metallic-circuit lines, and that the switches required for the two kinds of lines are the same. The confusion and trouble which would arise from two systems of switching and testing and two forms of switches for the two kinds of lines is avoided. sult is obtained by the combination of apparatus and circuits I have shown and described.

I claim as my invention and desire to secure by Letters Patent- 1. In a telephone-exchange system, a subscribers line permanently grounded at its outer end in combination with a switch for the line into which a double or loop plug is placed, said switch containing a contact-piece permanently connected to the line and a pair of contact-pieces which are normally in contact but which are separated by the plug on its insertion, one of said pair being connected to the line and the other, the third, being connected with the ground, one of the two contact-pieces of the plug being connected to a contact-piece of another plug and while inserted into the switch forming connection with said first contact-piece and the other contactpiece of the plu g forming connection with said third-mentioned contact-piece of the switch, respectively, substantially as set forth.

2. In a telephone-exchange system, a pair of double or loop plugs, one of the contactpieces of each of which is connected with one of the contact-pieces of the other, through flexible conductors, and the other contactpieces of which are connected with the ground through flexible conductors, and a metal contact-piece which, when the plug is in its normal position (or not in use for switching) connects the two contact-pieces of the plug together, (but not otherwise,) in combination `with a subseribers line grounded at its outer end, a switch for the line into which the other plug is'placed, and which then connects the line with said first-mentioned contact-piece of the plug, and an operators telephone between the first-mentioned contact-pieces of said plugs, substantially as set forth.

3. In a telephone-exchange system, a pair of double or loop plugs, one of the contactpieces of each of which is connected to one of the contact-pieces of the other, through This rel IOO IIO

flexible conductors, and the other contactthrough flexible conductors, and a metal conll l tact-piece which, when a plug is in its normal position,(o'r not in use for switchingg) connects the two contact-pieces of one plug together, (but not otherwise,) in combination with a single-circuit line grounded at its outer end, a switch for the line into which the other plug is placed, said switch containing a contactpiece connected permanently to the line and two other contact-pieces which are normally in contact, but which are separated by the y forth.l

4. In a telephone-exchange system, a subscribers line permanently grounded at one end and normally grounded at the central oiiice at the other end, in combination with a switch for the line into which a loop-plug is placed, said switch containing two contactpieces normally in the circuit of the line and in contact when the plug is not in the switch but not otherwise, and a third contact-piece permanently connected with the line, one of the contact-pieces of the plug being connected to a contact-piece of another plug and when thus inserted forming connection with said third contact-piece and the other contactpiece of the plug forming connection with the contact-piece of the switch which is grounded through the cut-onc portion of the line, substantially as set forth.

5. In a telephone-exchange system, a subscribers line permanently grounded at its outer end, in combination with switches for the line, one on each of several switchboards and into each of which double or loop plugs may be placed for switching, each swi tch containing a contact piece permanently connected with the line and two other contactpieces normally in contact but open while a plug is in the switch, said line passing, successively, through the pairs of contact-pieces and thence to the ground, one of the contactpieces of a plug being connected to a contactpiece of another plug and while inserted forming connection with said rst-mentioned contact-piece of the switch and the other contactpiece of the plug forming connection with the contact-piece of the switch, which is then connected with the ground substantially as set forth.

6. In a telephone-exchange system a subscribers line, in combination with switches for the line, one switch on each of several boards, and into which double or loop plugs may be placed for switching, two contactpieces normally in contact but open while a plug is in the switch, said line passing, successively, through the pairs of contact-points,

7. In a telephone-exchange system a subscribers line grounded at its outer end, in combination with a switch for the line into which a double or loop plug is placed for switching, said switch containing a contactpiece permanently connected with the line and two other contact-pieces which are normally in contact, but which are separated by the plug on its insertion, one of the pieces being connected with the line and the other with the'ground, one of the contact-pieces of the plug being connected with a contact-piece of another plug and the other being connected with the ground through flexible conductors, said first-mentioned contact-pieces of the plug and switch, and said last-'mentioned contactpieces of the plu g and switch, being connected together respectively, while the plug is inserted, substantially as set forth.

S. In a telephone-exchange system, a subscribers line grounded at its outer end, in combination with switches. for the line, one switch on each of several boards, and into each of which double or loop plugs may be placed for switching, each switch containing a contact-piece permanently connected with the line and two other contact-pieces normally in contact but open while a plug is in the switch, said line passing, successively, through the pairs of contact-points and thence to the ground, one of the contact-pieces of each switch-plug being connected with a contact-piece of another plug and the other contact-piece being connected with the ground, through iiexible conductors, said first-mentioned contact-pieces of a plug, on its insertion into a switch, forming connection with said first-mentioned contact -piece of the switch and the other contact-piece o f a plug forming connection with the contact-piece of the switch which is connected with the ground, substantially as set forth.

9. In a multiple-switchboard exchange, a single-circuit line having a common returnconductor, a jack-contact at two or more boards, permanently connected tos-aid single line, a metallic circuit, loop-switch apparatus having two cord conductors, one adapted to connect a contact of said single line to one limb of said metallic' circuit, and the other adapted to connect the other limb of said metallic circuit to said return-conductor.

10. In a multiple-switchboard exchange, two or more metallic circuits, two or more single-line circuits having a common return, a jack-contact at each board, permanently IOD IIO

,connected to each of said single lines, loopswitch apparatus having two cord conductors adapted to connect any two of said circuits together, so constructed that when two metallic circuits are connected together the two limbs of one are connected to the two limbs of the other by said two cord conductors respectively, and when a metallic circuit and a single circuit are connected together one of the jack-contacts of said single circuit is connected to one side of said metallic circuit by one of said cord conductors, and the other side of said metallic circuit is connected to said common return by the other of said cord conductors.

11. In a multiple-switchboard exchange, two or more sin gle-line circuits'having a common return, a j ack-contact at each board permanentlyconnected to each of said single-line circuits, two or more metallic circuits counected to said boards, the two limbs of each metallic circuit connected to two contacts respectively in each jack, loop-switch apparatus comprising two plugs each having two contacts connected together through two flexible cord conductors, one cord conductor adapted to connect the jack-contact of one of said single circuits with one limb of one of said metallic circuits andthe other cord conductor adapted to connect the other limb of said metallic circuit to the common return-conductor, and said loop-switch apparatus also adapted to connect together the two limbs of two metallic circuits.

12. In a multiple-switchboard exchange, a single-circuit telephone-line having a common return, a contact in each of several jacks permanently connected to said line, normally closed pairs of contacts in said jacks through which the line is normally connected to said common return and disconnect-ed by the insertion of a switch-plug; a metallic-circuit, loopswitch apparatus having two cord conductors, one cord conductor adapted to connect a permanently-connected jack-contact of the single-circuit line with one limb of said metallic circuit, and the other cord conductor adapted to connect the other limb of said metallic circuit to said common return.

13. In a telephone-exchange, a single-circuit line, an operators set, loop-switch apparatus adapted to connect said set to said single line, comprising two plugs, one carrying a contact adapted to make connection with said line, the other carrying two contacts normally cross-connected by a conducting base-plate, one of said contacts connected through the operators set to the said contact of the rst-nientioned plug, and the other contact connected to the return-conductor of said single-circuit line.

14. In a multiple-switchboard exchange, a single-circuit line continuous in the order named from a common conductor through a subscribers outfit, a line conductor, electrically-united test-contacts, one at each board, normally-closed jack-contacts, a set at each board, and a connection to said common conductor, and metallic circuits continuous in the order named from electrically-united testcontacts one at each board, metallic line conductors including a subscribers outfit, normally closed j ackcontacts,a set at each board, and a connection to said common conductor; in combination with loop-switchin g apparatus having two cord conductors adapted to connect said circuits, and thereby open a set of normally closed contacts, and test outfits, one at each board, including a test receiving instrument adapted to be connected to a testcontact of either line and thereby establish a circuit for testing while the line is not switched for use, but not otherwise.

15. In a multiple-switchboard exchange, singlecircuit lines, each continuous in the order named from a return-conductor through a subscribers outfit, a line conductor, testcontacts, one at a jack at each board, normally closed contacts, a set in a jack at each board, a rheotome, and a connection to said return-conductor; and metallic circuits each continuous in the order named from test-contacts, one in a jack at each board, metallic line conductors, including a subscribers outlit, normally closed contacts, a set in a jack at each board, a rheotome, anda ground connection; in combination with loop-switching apparatus comprising two plugs each having two contacts, a contact of one plug connected to a contact of the other plug through a flexible conductor containing an operators set, the other contacts of the two plugs connected together through a iiexible conductor connected to said return-conductor, thus adapted to connect together any two of said circuits, and operators test outfits, one at each board, adapted to be connected to a test-contact of any line for testing, each outiit including a test-plug, a test receiving instrument and test-battery, in a circuit connected to said rcturn-conductor.

In witness whereof I hereunto subscribe my naine this 29th day of November, 1889.

MILO G. KELLOGG.

Witnesses:

EMIL ABENHEIM, MARcAnE'ri-m Rini-in.

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